add a [mysql] block to our my.cnf that contains the database= settings

so that mysqldump and other utilities using this file don't get a
warning.

Note that we do not convert existing configuration so that
milestone:0.9.8 installs will have to be manually patched to remove
the warning on mysqldump.

See #1127 and ["Errata_0.9.8"].

install/mysql.sh

@@ -107,6 +107,9 @@ else
 # Automatically generated by AlternC configuration, do not edit
 # This file will be modified on package configuration
 # (e.g. upgrade or dpkg-reconfigure alternc)
+[mysql]
+database=
+
 [client]
 EOF
     chown root:www-data $MYSQL_CONFIG